Closures such as crown seals or caps are routinely used and are well known in the art for sealing the openings of containers or bottles which typically contain carbonated or other beverages. With respect to crown seals, they are commonly formed of metal sheet material and comprise a top and a sidewall with a flared skirt. The skirt includes a plurality of flutes which extend around the circumference thereof at spaced intervals. When applied to cover an open end of a bottle, these flutes are bent or crimped at the points of intersection between the top and the skirt, gripping a bead at the upper rim of the bottle opening for sealing.
To obtain a seal of sufficient strength which will withstand the pressure of the contained carbonated or other beverages, a metal such as steel typically is used to form crown seals. In order to provide an effective gas-tight seal, metal crown seals generally will include a sealing gasket or liner which is attached to the inside of the top of the crown seal. Such a liner commonly is made of plastic or a similar resilient material which provides a seal between the bottle opening and the metal crown seal when it is applied to the bottle.
In recent years metal "twist-off" crown seals have become more popular and are used by numerous beverage manufacturers. The twist-off crown seal generally includes internal threads which are formed when the flutes of the crown seal are bent or crimped onto the external threads located near the upper rim of the container or bottle opening. The twist-off crown seal is removed from the bottle without the use of a bottle opener by rotating the crown seal to unthread it from the bottle. The metal flutes are relatively sharp, however, and can be uncomfortable when grasped by a consumer when the bottle is picked up or opened. Particularly with the twist-off crown seal design, the sharp edges of the flutes can be painful as the crown seal is removed. With respect to tamper evidence, moreover, crown seals, particularly twist-off crown seals, can easily be replaced onto the bottles after being removed with little or no evidence that the bottles have been opened or tampered with.
As a result of the disadvantages and limitations noted for metal crown seals, the use of plastic closures for bottles containing pressurized beverages has been proposed in the prior art. Such prior art designs for plastic closure caps have several advantages over metal crown seals. Among the advantages are ease of use, low torque removal, better protection for the bottle finish, less possibility of injuring the user's hand during removal, less possibility of injuring others if carelessly discarded, and a potential for biodegradability.
Despite these advantages, however, the prior art plastic closures have suffered from a number of disadvantages which have limited their use in commercial applications. For example, in order to provide sufficient sealing integrity to ensure a gas-tight seal for extended periods of time, some plastics caps have been made to incorporate an inner skirt that enters the bottle mouth to pressure seal the contained beverage. Other plastic caps have included an outer strengthening collar for holding the closure on the bead of the bottle mouth. Still other plastic closures have combined the features of screwing completely onto the bottle for a tight fit while employing an inner skirt for added pressure seal. To incorporate these features, additional material, manufacturing steps and/or specialized machinery is required which increases the time and cost of manufacturing the caps sealing containers with such caps.
Another disadvantage of the prior art plastic closures is that the closures can be relatively easily removed by hand by persons tampering with bottles. Furthermore, with these prior art designs, there is no convenient way by which it is possible to determine or detect whether a bottle has been previously opened by an unauthorized person and then resealed.
Thus, metal crown seals and the prior art plastic closures for bottles or other containers are beset with drawbacks and problems. All of the above-mentioned disadvantages are minimized or eliminated by the present invention.